This invention relates to improvements in position control systems and methods for translating one member relative to another. More particularly, this invention relates to improvements in methods and apparatus for moving a data memory device member, such as a data transducer, relative to another member, such as a rotating disk having a multiplicity of available concentric data cylinders or tracks, and keeping the moved member in alignment with a selected track of the other member.
U.S. Pat. Application Ser. No. 06/190,198 was filed on Sept. 24, 1980, by Joel N. Harrison, Donald V. Daniels, and David A. Brown, for an invention entitled Data Transducer Position Control System for Rotating Disk Data Storage Equipment. That application, assigned to Quantum Corporation, the assignee of the present application, disclosed one solution to the problem of accurately controlling the position of a data transducer relative to selected ones of a multiplicity of adjacent concentric annular tracks. Reference to that application is suggested to those readers desiring further particulars. While that prior solution worked well and constituted a significant improvement over other prior art approaches available up to that point, it had the drawback of complexity in the electronic hardware thereof. Since then, significant further improvements have been made by the present inventors to increase reliability and capacity of the system and at the same time significantly reduce hardware complexity. These improvements are the subject of this patent application.